Comparative analysis of harmonic suppression on single phase conventional PWM rectifier and back to back PWM rectifier (original) (raw)
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Global Journal of Research In Engineering, 2016
Harmonic distortion is a huge problem for the power systems. But harmonic distortion can be controlled using some unique methods with the utility systems. This paper discusses the impact of using 12- pulse and 24-pulse rectifier circuit. The 24-pulse topology is generally more expensive, but produces the least Input current harmonics. In this paper pulsemultiplication technique is used to mitigate the harmonic distortion from the input line current. Phase-shifting transformers are used to produce 24-pulse from 12- pulse. A comparison between 12-pulse and 24-pulse rectifier also shown in this paper. Operation of the circuits is verified through computer simulations.
Improvement of Power Quality Using PWM Rectifiers
The paper presents the modeling, simulation and analysis of an AC-DC converter based PWM rectifier. It provides a suitable control algorithm for a pulse width modulation rectifier which reduces ripple from the DC output side as well as shapes the input current properly. The basic objective of a PWM rectifier is to regulate the DC output voltage and also ensure a sinusoidal input current and unity power factor operation. This is implemented by high speed IGBT switches connected in anti parallel mode across the rectifier diodes. The output voltage is controlled by switching these IGBTS and higher order ripples at the output can be easily eliminated with the help of passive filters. Lower order harmonics are eliminated using PWM technique. The control subsystem generates gating pulse to the universal bridge by passing the output voltage through a network consisting of comparator, discrete PI controller and discrete PWM generator. The output of this generator are the gating pulses to be applied to the universal bridge.
Comparative Study of Pulse Width Modulated and Phase Controlled Rectifiers
International Journal of Engineering Research and, 2015
Fixed DC voltage is one of the very basic requirements of the electronics' circuits in modern systems. Thus, single phase diode or thyristor rectifiers are commonly used in many industrial applications where we require a highpower DC supply or an intermediate DC link of AC/AC converters. The benefits include simple structure, high safety and most importantly, low cost. However, it is reasonable to assume that a price is to be paid for these benefits. The major drawback is the power system harmonics that these bridge rectifiers introduce within a system. The economic advantage that these systems enjoy can be nullified overnight if stricter harmonic standards are implemented. With this in mind, there is an increased interest in active filters and schemes like PWM that can counter these. The less prominent (but important from the consumers' point of view) issues include low power factor, voltage distortion, heating of transformer cores etc. A single standard scheme that can work for all applications is an ideal yet impractical solution. Thus, different schemes that have been introduced need to be compared so that it is easier to choose whichever fits best with the task at hand.
Study of Harmonic Content Elimination with Three Phase PWM Rectifier and Phase Controlled Rectifier
This Pulse width modulated rectifier is a very popular topic nowadays. The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. That is why the PWM rectifier is being examined. Here FPGA based controller is used to generate necessary pulses to drive the devices of the rectifier. In comparison with the phase controlled rectifier it can be controlled to consume nearly sinusoidal current with power factor equal to unity. Another advantage is its capability of energy recuperation. This paper deals with the PWM rectifier functional model realization and examination. PWM rectifier and phase controlled rectifier is compared on the basis of the input current harmonic analysis.
Analysis of Single Phase PWM Rectifier for Different Applications
Journal of The Institution of Engineers (India): Series B, 2016
This research work investigates the various applications of a PWM rectifier based on its input power factor. Most of the cases, the papers describe the operation of the rectifier used for unity power factor (UPF) operation. Beside this mode of operation, this paper compiles the application of the rectifier as STATCOM also, where the rectifier deals only with reactive power exchange. In this work, the controller is implemented by inserting a loop for reference input of phase angle which will be compared with the actual one, so that user can operate the rectifier at any power factor. Some basic formulae are derived for the input current, active power and reactive power based on which the control circuit is to be designed. Here two Proportional-Integral (PI) controllers are used. A brief description of tuning these two PI controllers is incorporated in this paper. Also some calculations are given to determine the harmonic factors of the input line current from which it is found that the rectifier when operated in each mode operation, the order of the harmonics are very low.
Harmonic Mitigation Method for the DC-AC Converter in a Single Phase System
Abstract-This project suggest a sine-wave modulation technique is to achieve a low total harmonic distortion of Buck-Boost converter connected to a changing polarity inverter in a system. The suggested technique improves the harmonic content of the output. In addition, a proportional-resonant Integral controller is used along with harmonic compensation techniques for eliminating the DC component in the system. Also, the performance of the Proposed controller is analyzed when it connecting to the converter. The design of Buck-Boost converter is fed by modulated sine wave Pulse width modulation technique are proposed to mitigate the low order harmonics and to control the output current. So, that the output complies within the standard limit without use of low pass filter.
2013
Electrical machines utilise power electronic devices to start, stop and run the machines smoothly and efficiently. The harmonics produced, distort the source current to be a non- sinusoidal current. Input power factor also suffers due to low displacement factor. The classical control of switching devices results into a poor power factor. The harmonic content of the input current is very high and thus there is a requirement of a large filter. Sinusoidal PWM control attempts to correct all the above shortcomings of an AC/DC converter. In this paper, an improvement in the input power factor and the total harmonic distortion is demonstrated by comparing conventional two pulse converter with a Sinusoidal PWM converter with appropriate switching scheme. The analysis is done using MATLAB SIMULATIONS and different conclusions are drawn.
MITIGATION OF HARMONICS USING THYRISTOR BASED 12 PULSE VOLTAGE SOURCE PWM RECTIFIER
IJRET, 2012
Three-phase thyristor rectifiers have been used in industries for obtaining a variable dc voltage, but they have a problem of including large lower-order harmonics in the input currents. For high-power applications, a 12-pulse configuration is useful for reducing the harmonics, but it still includes the (12m ± 1) th (m: integer) harmonics. In order to further reduce the harmonics, this paper proposes to supply a ramp wave voltage at the input of a 12-pulse phase-controlled rectifier. Theoretical investigation to reduce harmonics is presented, and a strategy to control the regulated voltage and unity power factor at input side based on 12 pulse modulation technique. This paper discuss the impact of using 3-phase and 12-pulse rectifier circuit commonly found in unity power factor at input ac mains and regulate output voltage. The 12-pulse topology is known to be more expensive, but produce the least input current harmonics. However, the latter statement is completely true under balanced line conditions. In practice, the lines are inherently unbalanced. Hence, the question of whether the 12-pulse rectifier will indeed perform better in terms of the harmonics injected to the line is still under on-going discussions. This presents the modelling and simulation of both rectifier topologies to compare their input current and regulated output voltage harmonics. The rectifiers are modelled using the MATLAB/SIMULINK simulation model and several common cases conditions will be simulated to compare their harmonic levels.
Digital implementation of harmonics reduction of three-phase boost rectifier
2010
The line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components to the control signal of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this paper a digital implementation of injecting six harmonic to the control signal of three-phase boost rectifier is shown. The digital implementation is carried out by using FPGA. In this study a sin-wave and a triangle-wave with six times the fundamental frequency and variable amplitude are digitally generated in the FPGA. Each signal is added to the dc control signal component of boost converter to be compared with digitally generated saw-tooth. The simulation and experimental results show that the THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the control signal of the boost converter and the angle of input three-phase voltage.